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Bronze ProPress dielectric union, press-fit and FNPT ends

Viega

Viega 79155 ProPress di-electric union trap 1/2" x 1/2

SKU CH-59E5-1BYMQ MPN 79155

Bronze di-electric union connects 1/2" press-fit copper to 1/2" FNPT for potable water up to 200 psi and 250 °F

  • TypeDrain Components
  • MaterialBronze
  • Press-fit connection installs without soldering
  • Bronze body resists corrosion in potable water
  • EPDM O-ring seals up to 200 psi
  • Di-electric union prevents galvanic corrosion
  • Rated for 250 °F maximum operating temperature

Viega ProPress di-electric union

The Viega 79155 is a bronze crimp union fitting designed for potable water systems. It connects a 1/2 inch copper tube via press-fit on one side to a 1/2 inch FNPT thread on the other. The built-in di-electric union prevents galvanic corrosion between dissimilar metals. It is suited for professional plumbing installations requiring a secure, solder-free joint.

Replaces threaded or soldered dielectric unions

This fitting upgrades installations that traditionally use separate dielectric nipples and threaded adapters or soldered connections. The ProPress press-fit end eliminates open flame and solder, reducing installation time and fire risk on site. The jump is worth it when working in tight spaces where torches are impractical or when codes require a dielectric barrier at copper-to-steel transitions. It streamlines the joint into a single, inspected component.

Handles 200 psi and 250 °F in potable water

The bronze body and EPDM O-ring are rated for a maximum operating pressure of 200 psi and a maximum operating temperature of 250 degrees Fahrenheit. This capacity covers standard residential and commercial hot and cold water distribution. Headroom runs out in high-pressure booster systems exceeding the pressure rating or in steam lines surpassing the temperature limit. It is not intended for gas, oil, or non-potable fluids.

Highlights

  • Press-fit connection installs without soldering
  • Bronze body resists corrosion in potable water
  • EPDM O-ring seals up to 200 psi
  • Di-electric union prevents galvanic corrosion
  • Rated for 250 °F maximum operating temperature

Specifications

TypeDrain Components
MaterialBronze
BrandViega
Model79155

Questions about this item

What size copper tube fits the press-fit end of the 79155 di-electric union?

The press-fit connection is sized for 1/2 inch copper tube and uses an EPDM O-ring to seal the joint when crimped with a ProPress tool.

Which step is often missed when installing this bronze union on a potable water line?

Installers sometimes forget to fully seat the copper tube until the depth mark hits the fitting shoulder before pressing, which leaves the O-ring unseated and causes leaks.

What part of the 79155 union will need replacement after years of hot water service?

The EPDM O-ring inside the press-fit end is the wear item; it should be inspected whenever the system is opened and replaced if it shows hardening or cracking.

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